Telephone system



June 20, 1944. F. KESSLER 2,352,107

TELEPHONE SYSTEM Filed Sept. 14, 1942 I 8 Sheets-Sheet l FIG.|

Lme First Toll Switch Selector Selector w To 7 Selectors l I i"- SecondLine Selector Swifch INVENTOR. FRANK KESSLER ATTORNEYS June 20, 1944.KESSLER 2,352,107

TELEPHONE SYS TEM Filed. Sept. 14, 1942 8 Sheets-Sheet 3 38-Mulflpled ToBanks or All Cg Trunk Finder Swifches Trur? Finder F 3 I 4? rom e.

SWIYCh 400 B|ur;ksI

.2 Intermediate 0.1..R. Trunk Circuit 26 39 39a ash 39c I O J O 39h 1 9s0 g Lo 50s 51! o V0502 2, 5 41 o la 5 06 507 508 5709 42m F42d 42c 42b42c 42h 425 g Trunk Finder I From Sel. Swrfch 500 Banks III Lost C.LR.Trunk Circuit 27 34 Trunk Flnder L Switch 600 v INVENTOR. FRANK KESSLERATTORNEYS Y June 20, 1944.

F. KESSLER 2,352,107

TELEPHONE SYSTEM Filed Sept, 14. 1942 I 8 Sheets-Sheet 5 step 540 R580Contr l fies res, H o fiwl Fame Lockqug 1 1 R550 Answer R590Intermediate Storage Circuit 53s 7 Start r 736 r-, 4987 4 997 I 61 52?INVENTOR.\

FRANK KESSLER AT'mRNEYS June 20, I944. F. KE$SLER ,3

TELEPHONE SYSTEM Filed Sopt. 14, 1942 s Sheets-Sheet 7 5 to rt CommonEquipment 3! nswer INVENTOR.

FRANK KESSLER BYaz'xlll,z"%z

ATTORNEYS June 20, 1944, F KES'SLER 2,352,107

TELEPHONE SYSTEM Filed Sept. 14, 1942" a Sheets-Sheet 8 F|G.8

P57 a L 'k l8 15 36 35c C I M a 35 Finder Selector l9- 7 v 7 2 To OtherPositionsJ fl Position Distributor i fig v [1"H 2 I mother Toll OperatorSwitchboard-P05. No. I

Answer f Operator Position Circuit Answer l6 Key 800 ll "sol aoz an 3'[L 8|2/Q v Operator 803 if8|3 Headset emf Unanswered Answered 8|8 were'820 ezr @822 8|6 49s 499 427 s27, 627

INVENTOR.

-FRANK,KESSLER BYMMMM v ATTORNEYS Patented June 20, 1944 I TELEPHONESYSTEM Frank Kessler, Lombard, 111.; assignorto Automatic ElectricLaboratories,

of Delaware.

Inc., a corporation Application September 14, 1942, Serial No. 458,254

acclaim; ('01. 179-27) The present invention relates to telephonesystems and, more particularly, to .improved apparatus for storing callsat a predetermined switching stage of a telephone system when the callhandling facilities which follow the predetermined switching stage areall busy.

It is an object of the present invention to provide an arrangement forstoring C L. R. calls to a toll operator switchboard during an intervalwhen the C. L. R. call handling facilities of the switchboard are allbusy, and for automatically routing the stored calls to the switchboardas the call handling facilities thereof become idle.

According to another object of the invention, the stored C. L. R. callsare routed to the operator switchboard to be answered in the same orderthat they are stored. e

It is another object of the invention to provide improved call storagefacilities of the character described wherein provisions are made foracknowledging the stored calls from an operator switchboard withoutreleasing the calls from storage. I 1

According to a further objectof the invention, provisions are madewhereby the calls can only be acknowledged from the operator switchboardin the same order as they are stored. e

In accordance with another object of themvention, the callstorageequipment is provided with a number of storage circuits eachcapable of storing one call, the circuits-are controlled to store callsin a predetermined order,- and each circuit is prevented from receivinga second call for storage until the initially established order ofcircuit use is exhausted. I

According to still another objectof the invention, improved facilitiesare provided forholding each storage circuit out of service-after a callstored therein has been abandoned or completed,

until the order of circuit use as determined by associated circuitdistributing equipment is e X hausted. z I

In accordance with another object of the in.-

vention, provisions are made for preventing the answer circuit overwhich thestored calls are automatic answer switchesimproved callstoragefacilities for storing incoming calls ahead of the th call answeringfacilities of the switchboard are busy, and for automatically routingthe stored calls through the answer switches to the switchboard as thecall answering facilities of the switchboard become idle. v

According to another object of the invention, the stored calls arerouted from the storage facilities through the answer switches overpreferred paths which differ from the paths over which unstored callsare normally routed through the answer switches to the switchboard.

The invention, both to its'organization and method of operation,together with further objects and advantages thereof, will best beunderstood by referenc to the specification taken in connection with theaccompanying drawings in which Figs. 1 to 8, inclusive, when laidside byside in numerical order, illustrate a telephone system havingincorporated therein the features of the invention briefly referred toabove.

In the illustratedembodiment of the invention,

in Fig. 1 of the drawings as extending to the substations A and B,respectively. The two lines l and 8 terminate in the ofiice innon-numerical line switches 9 and I0, respectively, which have access tothe numerically controlled switching equipment through which localconnections are set up and through which access may be gained to thetoll operator switchboard, as 1 shown in Fig. 8 of the drawings, (of theother subscriber lines extending to the central .ofiice is similarlyterminated in a line 1 switch. The numerically controlled switchingequipment provided in the central office includes .40,

Each

a plurality of first selectors, one of which is indicated at H; aplurality of groups of second selectors, one of which includes theconnector l2; and a plurality of groups of connectors, one

of which includes the connector IS. The line .trunk circuits 25, 26, and21 through which connections'v may be extended to the switching answerswitches during an interval when'all of equipment associated with thetoll operator switchboard. More specifically, each toll selectorincludes facilities for automatically effecting the selection of an idletrunk circuit in a selected group, for transmitting on and off hooksupervisory signals to the toll operator switchboard, for maintainingitself operated so long as it is held from a calling substation, and formaintaining ground potential upon its test wiper l4c after it has beenoperated to seize one of the trunk circuits to which it has access anduntil it is released at the substation from which it is being held.Although they may be of any desired type, such, for example, as thetwo-motion type which utilize switching mechanisms arranged for rotarymovement followed by vertical movement, the first and second selectors,the toll selectors and the connectors are preferably of the a well-knownStrowger type.

The toll operator switchboard, as schematically shown in Fig. 8 of thedrawings, is preferably of the well-known Crocker type and may beof thespecific form disclosed and claimed in Patent No. 2,167,710 grantedAugust 1, 1939, to Thomas F. Crocker. In brief, this board comprises anumber of operator positions, only the first of which is indicated inthe drawings, which positions are universal in that they are eachprovided with facilities for handling inwardand C. L. R. (combined linerecording) toll calls as well'as interposition calls. The equipmentindividual to each operator position includes anoperator positioncircuit having embodied therein an'operator headset and the usual keysand key controlled relays that are required for the answering of thecalls of different types, the routing of'the r ceived calls to theirproper destinations, and the supervision of theconnections overwhich thecalls are extended. Each position also has associated therewith a numberof finder-selector links which may be selectively associated with'theequipment of the position circuit and are utilized to routeincomingcalls to theposition circuit and in the extension of the calls to theirdestinations. More specifically considered, the illustrated firstposition of the switchboard includes an'operatorpo- .sition circuit l6having embodied therein an .operator headset8l5 andv having associatedtherewith a number of finder-selector links, one of which is indicatedat -l8 ."as comprising a finder or answer switch 19 and a selector orcall switch 20. For the purpose of automatically distributing callsincoming to the toll operator switchboard to the various positionsthereof, a position distributor 2| is provided having the function ofassigning the different positions to receive calls in 'a predeterminedorder. The toll operator switchboard equipment further comprises anumber of register senders together with facilities for automaticallyassociating idle ones of the senders with the different operatorposition circuits and the difierentlinks that are occupied with calls.In the interests of simplifying the disclosure, the details of theoperator position circuit IS, the links associated with this positioncircuit, the position distributor 2|, the register senders, and theequipment for automatically associating these senders with the differentoperator position circuits and links,, have not been shown. Thesevarious pieces of equipment may be of the-exact form disclosed in theabovecited Crocker. patent.

In order more easily to explain the improved C. L. R. call storagefacilities to which the features of the present invention areparticularly directed, it is noted that'the operator position circuit I5is provided with an answer key 800, an answer relay R8l0, and an answerbusy lamp 8H5, which are utilized in the acknowledging of C. L. R. callsthat have been placed in storage in the manner described below. Each ofthe other positions of the toll operator switchboard is also equippedwith the described facilities for acknowledging stored calls.

"The trunk circuits 25, 26, 21, etc. through which connections areextended to the toll operator switchboard from the subscriber linesterminating in the central oflice are identical in arrangement.Accordingly, only the details of the trunk'circuit 25 have beenillustrated in the drawings. Briefly considered, this circuit comprisesan answer relay R200, aslow-acting cut-off relay R2l0, a hold relayR220, a storage relay R230, 2. switching relay R210, and three timingrelays R240, R250 and R250. The first of these timing relays is of thewell-known pendulum type, while the second and last of the enumeratedtiming relays are of the slow-to-operate and slow acting types,respectively.

For the purpose of storing the C. L. R. calls that may be initiated-at atime when all positions of the toll operator switchboard are occupiedwith calls, a number of storage circuits 28. 29, '30, etc. are provided.These storage circuits each have access to storage trunks 38, 39,40,-etc. which individually extend to the different C. L. R. trunkcircuits 25, 26, 21, etc., and are identical in circuit arrangement.Accordingly, corresponding; circuit elements of the three circuits havebeen'identified byreference numerals differing only in the hundredsdigits thereof. Briefly considered, the storage circuit 28 comprises atrunk finder switch 400 of the well-known rotary type, a slow-to-operatestart relay R420, a step relay R425, a test relay R430, acut-off relayR440, a lookout relay R450, a marking relay R460, ananswer relay R490,an answercontrol relay R480. anda slow-to-release control relay R410. Thtrunk finder switch 400 includes five setsof contacts 401,- 402, 403,404 and 405, each having the required number of pointsto permit accessto be gained to allof the C. L. R. trunk circuits; wipers 408, 401, 408,409 and M0 individually associated with the five enumerated contactsets; and meanscomprising an operating magnet lll and a ratchet and pawlmechanism, not shown, for 'driving the enumerated wipers over thecontacts of their respective-associated contact sets.

- For the purpose of indicating to the opera- 'tors attending the tolloperator switchboard that C. L. R. calls have been placed in storage,call 822; etc. individual to the varisuitably multipled for are providedat each of and 8l9-are. provided at each position spectively, indicatethat certain stored C. L.R.

'calls remain unanswered, and that certain stored C. L. R. calls havbeenanswered. The enumerated signal lamps permit the operators attendingthe different positions of the switchboard to readily ascertain how manycalls are in storage and whether or not the stored calls have beenacknowledged or remain unacknowledged.

OPERATION or THE SYSTEM In considering the operation of the system, it

may first be assumed that a local call intended for the substation B isinitiated at the substation- A and that the numerical switches H, l2 andl3 are utilized in setting up the desired connection. When the receiverprovided at the calling substation A is removed from its supporting hookto initiate the call, a loop circuit including the conductors of theline I is completed between this substation and the line switch 9. Thisswitch operates in a well-known manner to select and seize the firstidle selector, such, for example, as the selector II, to which it hasaccess. When the selector H is seized through the line switch 9, thecalling loop circuit is extended to this selector and the usual dialtone signal is returned from the selector over the established loopcircuit to inform the calling subscriber that the dialing operation maybe started. When the first digit is dialed at the calling substation,the selector ll elevates its wipers to a position opposite the level ofbank contacts terminating the trunks leading to the second selectorsthrough which access is gained to the connectors of the group havingaccess to the desired line 8. Following this operation and during theinter-digit pause between the first and second digits, the wipers of theselector l I are automatically stepped over the contacts of the selectedlevel until a trunk leading to an idle one of the second selectors inthe selected group i found. In the present case, the second selector I2is selected and seized during the trunk-hunting operation of the firstselector I I. Incident to the seizure of this second selector, thecalling loop circuit is extended thereto so that the switch isconditioned to receive the impulses of the second digit. When this digitis dialed at the calling substation A, the selector I2 elevates itswipers to a position opposite the level of bank contacts terminating thetrunks leading to the connectors of the selected group. Thereafter andduring the inter-digit pause between the second and third digits, thewipers of the selector l2 are automatically rotated over the contacts ofthe selected level until a trunk leading to an idle connector of thegroup is found. In the case assumed above, the connector I3 is seizedduring the trunk-hunting operation of the selector [2. Incident to theseizure of this switch, a switch-through operation is effected in theselector 12, whereby the calling loop circuit is extended to theconnector I3. When this connector is seized certain of the controlrelays embodied therein, and more particularly the line and hold relaysthereof, operate to condition the connector to receive the impulses ofthe third and succeeding digits of the directory number designating thedesired substation B. The first of these digits as dialed into theconnector l3 from the calling substation is utilized to position thewipers of the connector l3 opposite the level of bank contacts at whichthe group of ten lines, including the called line 8, is terminated. Thefourth digit as dialed into the connector l3 from the callingsubstation, is utilized to position the wipers of the connector on thecontacts at which the conductors of the called line 8 are terminated. Inaccordance with conventional practice, suitable provisions are made inthe connector 13 for testing the selected line 8 to determine the idleor busy condition thereof, for returning the usual busy tone signal overthe established loop circuit to the calling subscriber in the event thecalled line is busy, and for projecting ringing current over theselected side of the called line 8 in the event this line is idle.Assuming that the called line is idle. the called substation B issignaled in the usual manner through the transmission of ringing currentover the line 8. The desired conversational circuit between the callingand called substations is fully completed when the call is answered atthe called substation B. More particularly, when the receiver at thissubstation is removed from its supporting hook or cradle, a directcurrent conductive bridge is connected across the conductors of the line.8 ;to complete the usual circuit for energizing the ring cut-off relayin the connector I3. This relay, in operating, functions to arrest thetransmission of ringing current over the line 8 and to establish thedesired talking circuit between the calling and called lines in anentirely conventional manner.

Preferably, the control relays of the connector l3 are so arranged thatthe release of the operated switch train is entirely under the controlof the calling subscriber at the substation A. With such an arrangement,when the connection is cleared out at the calling substation A, the loopcircuit extending from this substation to the connector I3 isinterrupted to cause the release of the line and hold relays embodied inthis connector in the usual manner. When these relays restore, theselectors l2 and l l, the line switch 9, and the connector I3 are allrestored to normal in a manner well understood in the art. Incident tothe release of the line switch 9 and the connector [3, the privateconductors of the lines I and 8 are disconnected from ground to markthese lines as idle in the connectors to which they are respectivelyaccessible.

0. L. R. toll calls Referring now more particularly to the mannerinwhich C. L. R. toll calls are handled in the system, it may be assumedthat a toll call requiring the assistance of an operator at the tollswitchboard is initiated at the substation A, that the call is handledat the No. 1 position of the switchboard in the regular manner, that thefirst selector H, the toll selector l4, and the C. L. R. trunk circuit25 are utilized in routing the call to the toll operator switchboard,and that the link l8 individual to the No. 1 position of the switchboardis utilized in forwarding the call to its destination. After aconnection is extended from the line I to the first selector II and thedial tone signal is returned over the line I to inform the callingsubscriber that the dialing operation may be started,.the first digit ofthe toll directory number may be dialed at thissubstation. The impulsesof this digit as transmitted to the selector H are utilized to positionthe wipers of this selector opposite the level of bank contacts at whichare terminated the trunks extending to the toll selectors. Incident tothe vertical movement of the selector wipers the dial tone signal isterminated in the usual manner. During the interdigit pause betweenthefirst and second digits, the selector ll operates automatically toselect the trunk extending to the first idle toll selector which, .inthe case under consideration, is assumed to be the selector I4. Whenthis selector is found by the preceding selector H, the calling loopcircuit is extended thereto and the toll selector is conditioned torespond to the impulses of the second digit of the toll directorynumber. When this digit is dialed at the calling substation, the wipersof the toll selector I 4 are elevated to a position opposite the levelof bank contactsat which the trunk conductors of the C. L. R. trunkcircuits are terminated. At the end of the digit, the selectorfunctions-automatically to select and seize the first idle trunk circuitof the group. In

searching for an idle trunk circuit, the toll selector I4 looks fornegative battery potential on the test leads of the trunks extending tothe'various trunk circuits. Thus when the trunk circuit 25 is idle,negative battery potential is applied to the test conductor 320 over apath which includes' the winding of the relay R200 and the contacts 2 I4. In'the present'example, the C. L. R. trunk'circuit 25 isseized duringthe trunk-hunt ing operation of-the toll selector l4. As previouslyindicated, this'toll'selector is of the calling' party release type, notrequiring the completion of a holding circuit in a succeeding switch inorder to maintain itself operated after a trunk circuit has been seizedtherethrough. Moreover, this selector is provided with the usual relayfacilities for impressing ground potential upon its test wiper l4cincident to its operation to seize an idle succeeding switch.

When ground potential is applied to the wiper |4c in the toll selectorI4, a circuit including this wiper, the conductor 32c and the contacts2|4 is completed for energizing the answer relay R200. In operating, therelay R200 closes a circuit through the condenser 218 and the contacts20| and 212 for transmitting ringing current back over the calling endof the connection to produce the usual ring-back tone signal at thecalling substation A. The calling subscriber is thus informed that thecall is being extended to the toll operator switchboard. At its contacts203, the relay R200 prepares the operating circuit for the cut-ofi relayR2 0. At its contact 204, the relay R200 completes an obvious circuitfor energizing the hold relay R220. At its contacts 205, the relay R200completes a circuit for energizing the timing relay R240, this circuitextending from the normally grounded A. T. B. lead 209 by way of'thecontacts 205, 236 and 263, and the winding of R240 to battery. At itscontacts 202, the relay R200 completes a path through the contacts 232for impressing ground potential upon the start lead 265 extending to theposition distributor 2|.

The hold relay R220, uponoperating, opens its contacts 22| to disconnectthe terminating impedance bridge comprising the resistor 206 and thecondenser 20'! from the talking conductors 32a and 32b of the trunk 32.At its contacts 222, the relay R220 prepares a multiple circuit forenergizing the cut-01f relay R2l0. At its contacts 223, the relay R220prepares a locking circuit for itself. At its contacts 224, the relayR220 opens a point in the path for impressing ground potential upon thetest conductor 320 in the trunk circuit 25.

The timing relay R240, upon operating, attracts its weighted armature242 to close the contacts 243 and 244 and thus complete a circuit forenergizing the slow-to-operate timing relay R250. This circuit extendsfrom the grounded A. T. B. lead 209 'by' way of the contacts 205, 236,243 and 244, and the winding of R250 to battery. In operating, the relayR250 locks to the grounded lead 209 over a path which includes thecontacts 253, 243, 236 and 205. At its contacts 25l,-the relay R250opens a point in the operating circuit for the storage relay R230. Atits contacts 252, the relay R250 completes the operating circuitfor theslow-acting timing relay R260, this circuit extending from the groundedA. T. B. lead 200 by way of the contacts 205,

236 and 252, and the'winding of R260 to battery.

The timing relay R260, upon operating, closes its contacts 262 toprepare the operating circuit for thestorage relay R230. At itscontacts263, the relay R260 opens the operating circuit for the timing relayR240. When the latter relay is deenergized, its weighted armature 242 isreleased and starts to vibrate so that the contacts I and 243 arealternately closed. Each time either of the two sets of contacts MI and243 is engaged, a current pulse is transmitted through the winding ofthe timing relay R250. This relay is slugged so that it remains operatedso long as it is periodically energized. After a predetermined timeinterval elapses, the amplitude of vibration of the armature 242 isdecreased by an amount such that the contacts24| and 243 are no longerclosed thereby. At the end of this interval, the relay R250 isdeenergized and restores to perform the functions described below.

During the time interval measured by the operation of the three timingrelays R240, R250 and R260, in the manner explained above, the call asrouted to the C. L. R. trunk circuit 25 is extended to the No. 1position of the toll operator switchboard. More specifically, if thisposition has been allotted by the distributor 2| to handle the call,and'the talk key of the link |8 has been'operated to set this link upfor use in handling the call, the application of ground potentialto thedistributor start lead 265 serves automatically to initiate theoperation of the finder I9 to search for'thetrunk 32 extending to thetrunk circuit 25. Thu'sjwhen this start lead is connected to ground,

the start relay of the distributor 2| operates to impress groundpotential 'upon the start lead of the position circuit |6. The positioncircuit start lead is connected through the contacts of the talk key inthe link l8 to the start relay of this link. This relay, when energizedover the position start circuit, functions to initiate vertical movementof the wipers of the finder l9. In this regard, it is noted the verticalposition of the trunk 32 in the banks of the position link finders ismarked by the application of ground potential to start lead 265 thislead being connected to a level marking contact in the contact banks ofeach finder. When this level, as marked in the banks of the finder I9,is found, vertical movement of the finder wipers is arrested and rotarymovement of these wipers is automatically initiated. Such rotarymovement of the finder wipers continues until the trunk 32 is found, therotary position of the trunk 32 in the selected contact level beingmarked by the application of negative battery potential to the testconductor 32d over a path which includes the upper winding of the cutoff relay R2| 0, the contacts 203 and 222 in parallel, and the contacts23I. When this trunk is found the cut-off relay R2"! is energized inseries with the switching relay of the finder l9. Incident to theoperation of the latter relay, the rotary movement of the finder wipersis arrested and a talking circuit is set up over the talking leads ofthe trunk 32, the talking wipers of the finder I9, and the conductors823 and 8240f the operator position circuit to connect the operatorheadset 8l 5 withthe telephone instrument provided at the callingsubstation A.

When energized in series with the switching relay of the finder |9, thecut-off relay R2l0 closes its contacts 2 to prepare a holding circuitfor itself. At its contacts 2|2, the relay R2l0 prepares a lockingcircuit for the switching relay R210. At its contacts M3, the relay R2|0completes a locking circuit for the hold relay R220, this circuitextending from the grounded test wiper I40 of the toll selector l4 byway of the conductor 320, the contacts 2l3 and 223, and the winding ofR220 to battery. At its contacts 2, the relay R2l0 deenergizes theanswer relay R200.

In releasing, the answer relay R200 opens its contacts 20! to interruptthe ring-back tone signaling circuit and thus terminate the ring-backsignal being produced at the substation A. At its contacts 202, therelay R200 disconnects the distributor start lead 265 from ground,thereby to interrupt the level marking path described above and todeenergize the start relay of t e position distributor 2| in the eventno other toll calls are awaiting operator assistance for completion. Atits contacts 203, the relay R200 opens a multiple point in the operatingcircuit for the cut-off relay R2I0. At its contacts 204, the relay R200opens the operating circuit for the hold relay R220. At its contacts205, the relay R200 opens a point in the common portion of the operatingand locking circuits for the three timing relays R240, R250 and R260,causing any operated ones of these relays to restore. In the presentcase the release of the timing relays is without eifect.

After the connection has been extended to the No. 1 position of the tolloperator switchboard, the operator attending this position may conversewith the calling subscriber to ascertain the destination of the call andmay extend the connection to the desired exchange or substation, in themanner clearly explained in the previously cited Crocker patent. Forexample, the connection may be extended through the selector 20 and thetoll switch train I! .to the line l5 serving the substation C, it beingunderstood in this regard that a portion of the toll switch train I1 islocated in an exchange distant from the central exchange in which thetoll operator switchboard is provided. After the call is routed to itsdestination and answered at the called substation, the operatorattending the No. 1 position of the switchboard may, by suitable keyoperations, disconnect the position circuit Hi from the link l8 occupiedwith the call and rely upon the supervisorysignal lamps individual tothe link l8 for the production of signals which will enable her tosupervise the connection. In this regard it is pointed out in theCrocker patent referred .to above that suitable provisions are made inthe position circuit l6 and the links individual to the No. 1 positionfor enabling an operator attending this position to reenter a connectionset up through any one of the links, to split a connection set upthrough any one of the links, or to 2 monitor a connection set upthrough any one of the links. Provisions are also made in the positionequipment for guarding each position against distribution when theposition circuit thereof is operatively associated with any one of thelinks individual thereto. Thus, so long as the illustrated positioncircuit is occupied with the call under consideration it is marked asbusy in the position distributor 2|. When, however, the connection isestablished between the calling substation A and the desired substation,such, ,for example, as thesubstation C, and the operator attending theNo. 1 position disconnects her position circuit from the link [8, theNo. 1 position is marked as idle in the position distributor 2| and isthus rendered available for use in handling other calls. It is furtherpointedout that immediately the-call isextended to the No. 1 ;positionin the manner-explained above, the position distributor 21 operatesautomatically to select for use another of the available operatorpositions that is marked as idle in the distributing equipment.

Further to consider the call'as extended from the substation A to theNo. 1 position of the toll operator switchboard, it is noted that theoperator handling the call at this position does not release the link l8through which the call is forwarded to its destination until call andanswer disconnect signals are produced by appropriate control of thecall and answer supervisory lamps individual to this link. In thisregard it will be understood that when the called subscriber at thesubstation C, for example, releases the connection, an on-hooksupervisory signal is produced by the supervisory lamp individual to thecalled end of the connection. Similarly, when the calling subscriberatthe substation A disconnects, an on.-hook supervisory signal isproduced by the supervisory lamp of the link l8 which is individual tothe calling end of the connection. More specifically, when the callingsubscriber at the substation A disconnects, the toll selector M, thefirst selector H, and the line switch 9 are released in the order namedand in a manner well understood in the art. Incident to the release ofthe toll selector 14, the test wiper I4c thereof is disconnected fromground to deenergize the hold relay R220. In restoring, the relay R220opens its contacts 223 iurther to interrupt its own looking circuit and,at its contacts 224, connects the test conductor 320 to ground, therebyto maintain the trunk circuit 25 marked as busy in the banks of the tollselectors to which it is accessible. At its contacts 222, the relay R220opens the circuit for d rectl erg in the upp winding of the cut-effrelay R210 in series with the marginal supervisory relay provided in thelink L8, After these contacts are opened, the two windings of thecut-off relay R2I0 are connected in series with the winding of thesupervisory relay in the link [0 over a high resistance path whichincludes the contacts 2i I, the resistor 225, the eontacts 2 31, and thetest conductor 32d, The resistance of this circuit is such that thesupervisory relay of the link I8 is released although the cut-offrelay-R2I0 is held in its operated position. When this supervisory relayrestores, the usual on-hook supervisory signal is produced by the answersupervisory lamp provided in the link 18.

The operator, upon receiving the disconnect signals in the mannerexplained above, may reoperate the talk key of the link l8 in order toassociate this link with her position circuit l6, and then actuate theanswer and call release key of the position circuit in order to initiatethe release of the link. The manner in which these operations areeffected is clearly explainedin the above-cited -Crocker patent.Incident to the release of thelink [8, the circuit for energizing thesupervisqryrela of the ;link in series'with e two windings o the u ofi eay R2 is b oken. Whe thu deenerei ed h l y R201 res e es and o ens itson ac s 21 o is n t the test o tor3. f9m ound. t i s tacts 214, therelay 1132,!0 connects the test condilator 1320 throu h the w di o t e aswe relay R2110 .1 0 the negative terminal of the exchange battery.whereby the trunk circuit 25 is marked idle in the bank contacts of the.toll selectors. In releasing, the relay R2 l 0 also opens its contacts.2, further to interrupt the above- .deseribed .high resistanQ-e holdingcircuit for itself. At its contacts2- l2, the relay R2l0 opens a pointin the locking circuit for the switching relay R210. Following therelease of the cut-oft relay R210, the trunk circuit is fully restoredto normal and'is conditioned for further use.

0. LR. CALi. STORAGE l As indicated in the above explanation, the cutoffrelay R210 is operated to terminate the timing operation of the threerelays R240, R250 and R260 in response to the operation of one of theposition link finders to seize the trunk- 32. This will obviouslynotoccur if all of the active positions of the tollfoperator switchboardare occupied with calls at the time the above-described call originatingat the substation A is extended to the trunk circuit 25. Accordingly,the timing operation of the three enumerated relays is permitted tocontinue, with the result that the call under consideration is'placedinlstorage- More specifically, when the timing relay R250 restores,inthe manner explained above, it opens its contacts 253 further tointerrupt its own locking circuit and, at its contacts 252,'todeenergize the timing relay R250. At its contacts 251, the relay R250completes the prepared operating circuit for the storage relay R230,this circuit extending from the grounded A. T, B. lead 209 by way of thecontacts 205, 236, 25! and 262, and the winding of R230 to battery. Thereleaseof the timing relay R260 shortly after the storage relay R230operates is without effect.

In operating, the relay R230 first locks to ground through itspreliminary. make contacts 235 and the contacts 204. At its contacts236, the relay R230 then opens its own operating circuit as well as theoperating and locking circuits for the timing relays R240, R250 andR260. At its contacts 231, the relay R230 disconnects the test conductor32d from the negative terminal of the exchange battery, and opens apoint in the above-described path for marking the rotary position of thetrunk 32 in the banks of the position link finders and a point in theoperating circuit for the cut-off relay R2l0, At its contacts 232, therelay R230 disconnects the start lead 265 from ground. Following the twolast-mentioned operations the trunk circuit 25 isno longer marked asacalling trunk circuit in the position distributor 2| and in the banksof the position link finders having access thereto. 'At its contacts233, the relay-R230 prepares the operating circuit for the switchingrelay R210. At its contacts 234, the relay R230 completes an obviouspath for impressing ground potential upon the test conductor 38s,thereby to mark thetrunk circuit 25 in the bank contacts of the trunkfinder switches 400, 500, 600, etc. individual to the various storagecircuits 28, 29, 30, etc. At, its contacts 231, the relay R230 completesa circuit .for energizing the start relay of ,the particular storagecircuit which has been preselected for use in storing the call. In thisregard it may be assumed that all of the storage circuits are idle, inwhich case the call as extended to the trunk circuit 25 will be storedin the first storage circuit 28. Thus when the storage relay R230operates,

, the slow-to-operate start relay R420'is energized in a circuit whichextends from ground by way of the contacts 231 and 211, the start lead214 common to the several C. L. R, trunk circuits, the

contacts 436 and 456, and the winding ofR420 to battery. I

In operating, the start relay R420 closes its contacts 422 to prepare acircuit for energizing the upper winding of the step relay R425 inseries with the upper winding of the test relay R430. At its contacts423, the relay R420 opens a point in the common portion of the circuitover which the start relays of the second and succeeding storagecircuits may be operated, thereby to prevent a later initialed C. L. R.call from being routed to storage before the call under consideration isfully extended to the storage circuit 28. At its contacts 42 l, therelay R420 completes the prepared operating circuit for the steppingmagnet 41 l of the trunk finder switch 400, this circuit extending fromground by way of the contacts 432, 426 and 42l, the conductor M122, andthe winding of the magnet 4!! to battery. When thus energized, themagnet M l closes its contacts M2 to complete a circuit over theconductor 4| d for energizing the lower winding of the step relay R425.This relay, in operating, opens its contacts 426 to deenergize themagnet 4. In releasing, the magnet 4H advances the wipers 406, 401, 408,409 and M0 one step and opens the contacts M2 to deenergize the steprelay R425. In restoring, the relay R425 closes its contacts 426 toagain energize the magnet 4| I. The inter-related operation of themagnet 4H and the step relay R425 continues until the wipers of thetrunk finder switch are positioned on the contacts terminating theconductors of the trunk 33 extending to the trunk circuit 25. At thistime, a circuit is completed for energizing the series-connected upperwindings of the step relay R425 and the test relay R430. This circuitextends from ground by way of the contacts 234 and 216, the test lead38s, the wiper M0, the conductor 4ls, the contacts 422, the upperwinding of R425, and the upper winding of R430 to battery. When itsupper winding is thus energized the relay R425 is prevented fromreleasing to recomplete the operating circuit for the stepping magnet 41l. Thus the step by step operation of the trunk finder switch 400 isarrested with the wipers of this switch standing on the contactsterminating the conductors of the trunk 38.

The test relay R430 also operates when its upper winding is energized inthe above-traced test circuit. In operating, this relay opens itscontacts 432 further to interrupt the operating circuit for the steppingmagnet 4! l, and closes its contacts 433 to prepare a circuit forenergizing the start relay R of the common equipment 3|. At its contacts434, the relay R430 completes a locking circuit for itself, this circuitextending from ground by way of the contacts 124, 484, 461 and 434, andthe lower Winding of R430 to battery. At its contacts 43l, the relayR430 completes a circuit for energizing the switching relay R210 inseries with the marking relay R460, this circuit extending from groundby way of the contacts 233, the winding of R210, the conductor 38h, thewiper 409, the conductor 4Ih, the contacts 43l and 45l, and the Windingof R460 to battery. At its contacts 436, the relay R430 interrupts theabove-traced operating circuitfor the start relay R420. At its contacts435, the relay R430 prepares the operating circuit'fo'r the start relayR520 of the next succeeding storage circuit 29. At its contacts 431, therelay R430 completes a circuit for energizing the signal lamp 820individual to the storage circuit 28 and provided at the No. 1 positionof the toll operator switchboard, and parallel circuits forenergizingextends from ground by way of the contacts 431., the conductor 421 andthe parallel-connected filaments of the several signal lamps to battery.The energization of these lamps serves to inform the operators inattendance at the toll operator switchboard that a C. L. R. call hasbeen stored inthe first storage circuit 28 which should be acknowledged.

The marking relay R460 operates when energized in series withtheswitching relay R210 in the manner explained above. Upon operating. therelay R460 closesits contacts 462 to complete an obvious holding circuitfor itself. At its contacts 463, the relay R460 opens a point in thecircuit for energizing th lower winding of the cut-01f relay R440. Atits contacts 465, the relay R460 opens a point in available circuits forenergizing the relays R430, R440 and R450. At its contacts 464, therelay R460 completes an obvious circuit for energizing the control relay4 R410. At its contacts 466 and 461, the relay R460 first closes anobvious alternative locking circuit for the test relay R430 and thenopens the locking circuit for this relay as initially completed throughthe contacts 124 of the reset slave relay R120. At its contacts 468, therelay R460 prepares a circuit for energizing the answered signal lamps819 as individually provided at the different positions of the tolloperator switchboard, and completes a circuit for energizing theparallel-connected unanswered signal lamps MS as provided at thedifferent positions of the switchboard. The latter circuit extends fromground by way of the contacts 468 and 458' the signal lead 498 and theparallel-connected filaments of the unanswered signal lamps 8l8 to thenegative terminal of the exchange battery. At its contacts 46l, therelay R460 connects the test conductor 350 of the trunk 35 to thenegative terminal of the exchange battery over a path which includes thecontacts 46 I, 445 and 493, and the upper winding of the cut-off relayR440. Completion of this path serves to mark the rotary position of thestorage trunk 35 in the bank contacts of the position link finders andto prepare a circuit for energizing the cut-ofi relay R440.

The control relay R410, upon operating, closes its contacts 413 toprepare the above-mentioned circuit for energizing the lower winding ofthe cut-off relay R440. At its contacts 412, the relay R410 completesthe prepared operating circuit for the start relay R100, this circuitextending from ground by way of the contacts 433, 446, 412 and 494, andthe winding of R100 to battery. At its contacts 414, the relay R410prepares circuitsfor energizing the relays R430, R440 and R450. At itscontacts 415, the relay R410 disconnects the A. T. B. lead 209 fromground in the first storage circuit 28, thereby to open one of themultiple paths over which the storage and timing relays of the various0. L. R. trunk circuits 25, 26, 21, etc., may be energized. At itscontacts 41!, the relay R410 completes a circuit for transmittingringing current over the calling end of the connection in order tocontinue the ring-back tone signal being reproduced by the receiver ofthe telephone instrument provided at the calling substation. The circuittraversed by the ringing current following the r 41] and 44!, thetalking conductor am, the wiper 401, the talking conductor 38b,'and'the" contacts 213 to the positive side of the'taliilng-v cir-' cuitas established between the trunk circuit and the'toll selector l4. Fromthis conductor the ringing current is further transmitted through thefirstselector H and the line switch 0 to the conductors of the line 1'and over these conductors to energize the receiver provided at thecalling substation.

As indicated above, the switching relay R210 I is energized in serieswith the marking relay R460 incident to the operation of the test relayR430 In operating, the switching relay R210 closes its contacts 215 toprepare a locking circuit for itself. At its contacts 216, the relayR210 opens the above-traced circuit for energizing the series-connectedupper winding of the step relay R425 and the test relay R430, causingthe first of these relays to restore. At its contacts 211, the relayR215 disconnects the start lead 2 from ground, thereby to prevent thestart relay, such, for example,- as the relay R520, of a succeedingstorage circuit from being operated. At its contacts 21l and 213, therelay R210 connects the talking conductors 32b and 32a to the talkingconductors Mb and 4 la over paths whichrespectively include the trunkconductors 38b'and 38a and the wipers 401 and 406. At its contact's 212,the relay R210 opens the initially completed circuit for transmittingringing cu-r'rent over the calling end of the connection to produce theusual ring-back tone signal at the calling substation. At its contacts214, the relay R210 prepares an alternative operating circuit -for thecut-01f relay R2l0. I i

As pointed out above, the startrelay R420 is deenergized incident to theoperation of the test relay R430 and in response to the'operation of thetrunk finder switch 400 to select the trunk 36 extending to the trunkcircuit 25. The step relay R425 is deenergized in response to theoperation of the switching relay R210immediately the storage circuit 20is seized. The relay R420, upon restoring, opens its contacts 42ffurther to interrupt the operating circuit for the stepping magnet 4Hand, at its contacts 422, interrupts the circuit for energizing theseries c'onnected upper windings of the step relay R425 and the testrelay R430. At its contacts '423, therelay R420 further prepares theoperating'circuit for the start relay R520, of the next succeedingstorage circuit. In this regard it may be noted that normally theswitching relay R210 will be operated to open the start circuit at its"contacts 211'before the start relay R420 is released to extend thestart circuit tothenext succeeding storage circuit. In any event, theperiod during which the start circuit as extended to the next succeedingstorage circuit is completed through the contacts 23-1, 211, 435and 423,will be insufficient to cause the operation of the start relay in thesucceeding storage circuit. The release of the step relayR425' iswithout efiect.

It is also pointed'out above that when the control relay R410 operates,a circuit iscompleted for energizing the start relay R of the commonequipment 3!. The-latter relay, upon operating, opens its contacts 102to interrupt the incomplete but 'available circuit for energizing theslow-to-op'erate reset relay R1I0. At its contacts 104, the relay R100connects the start lead to ground, thereby to mark the vertical level ofbank contactsof the position link finder in which the storage trunks 35,36, 31, etc}, of the various trunk circuits are terminated; and also toprovide a circuit for energizing the start relay in the positiondistributor 2|. It is noted in this regard that the storage trunks areterminated in a level of the position link finder banks which is lowerthan the levels used to terminate the regular C. L. R. trunks 32, 33,34, etc., whereby any finder, during its vertical searching operation,will find the storage trunk level before it reaches the regular'trunklevels. By virtue of this arrangement, the stored C. L. R. calls aregiven preference over later initiated C. L. R. calls in the handling oithe. calls at the operator switchboard. I I

" Release from storage before acknowledgment From the above explanationit will. be understood .that with the marking relay R460 of the storagecircuit 28 and the start relay R100of the common equipment 3| operated,the trunk 35 is marked as a calling trunk both in the bank contacts ofthe position link finders and in the position distributor 2 Accordingly,if one of the positions of the toll operator switchboardbecomes idlebefore the stored call is acknowledged at this switchboardthe'position'is selected by the distributor 2| to handle the stored calland the finder portion of the link set up for use by theoperator-attending this position is operated to searchfor the trunk 35in the manner'previously explained. Assuming that the illustrated No. 1position is selected to handle the call, and further that the link I8 isset up for use-by the operator in attendance at this position, thecut-off relay R440 is energized in series with the switching relay ofthe finder |9 when the wipers of this finder are positioned to engagethe bank contacts at which the conductors of thetrunk 35 are terminated.More specifically, the operating circuit for the cut-off relay R440extends from ground through the operating winding of the switching relayin the link finder l9 by way of the test wiper of the finder I9, thetest conductor 350 of the trunk 35, the contacts 461, 445 and 493, andthe upper winding of R440 to battery. When thus energized, the switchingrelay oi the finder l9 operates to preparea. talking circuit includingthe trunk conductors35a and 35b which is extended tothe operator headset8|5 in the operator position circuit IS.

The cut-01f relay R440 also operates when energized in theabove-described test circuit, and in so doing first closes itspreliminary make contacts 441 to complete a locking circuit for itselfwhich includes its lower winding and the contacts 466.

Atits contacts 446, the relay R440 deenergizes the startrelay R100 ofthe common equipment 3|. .At its. contacts 441, the relay R440 preparesalternativelocking circuits for itself and the test relay R430. At itscontacts 448, the relay R440 prepares one point in an available chainpath for .iriipressingtground potential upon the A. T. B.

lead 209. At its contacts 449, the relay R440 opens a point inthe'circuit for energizing the answered signal lamps as provided at thedifferent'positions of the toll operator switchboard. At'its contacts444, the relay R440 completes a circuit for energizing the upper windingof the cut-oil relay R2|0 in series with the operating winding ofthesupervisory relay provided in the link H l8, this circuit extending fromground through the operating winding of the supervisory relay :by way ofthe test wiper of the finder I9, the test conductor 350 of the trunk 35,the contacts 4 6|-and;4 44, the conductor4lc, thewiper 408, the

conductor 380, the contacts 214, the parallel-connected contacts 203 and222, and the upper winding of R2|0 to battery. After this circuit iscompleted, the relay R440 opens its contacts 445 to interrupt thepreviously traced circuits for energizing its upper winding first inseries with the operating winding of the switching relay in the linkfinder l9 and thereafter in series with the operating winding of thesupervisory relay provided in this link finder. At its contacts 442 and443, the relay R440 connects the talking conductors 35b and 35a of thetrunk 35 to the talking conductors 4|b and Ma of the trunk 4|, therebyto complete a talking circuit between the calling substation and'theoperator headset 8|5. At its contacts 44|, therelay R440 interrupts thepreviously described circuit for transmitting ringing current over thecalling end of the connection, whereby the ring-back signal beingreproduced at the calling substation is terminated. At its contacts441', the relay R440 also completes a circuit for energizing the lookoutrelay R450, this circuit extending from ground by way of the contacts406 and 441 and the series-connected windings of the relay R450 tobattery.

When thus energized, the relay R450 locks to ground through itspreliminary make contacts 452 and the contacts 466. At its contacts 453,the relay R450 opens a point in the circuit for energizing its lowerwinding in series with the resistor 438. At its contacts 454, the relayR450 opens another point in the path for impressing ground potentialupon the A. T. B. lead in the storage circuit 28. At its contacts 454',the relay R450 further prepares the above-mentioned chain path forimpressing ground potential upon this lead. At its contacts 455, therelay R450 prepares an alternative path for extending the storage startcircuit to the next succeeding storage circuit. At its contacts 456, therelay R450 opens another point in the operating circuit for the startrelay R420. At its contacts 451, the relay R450 opens a point in theoperatingcircuit for the answer relay R490. At its contacts 451, therelay R450 prepares the operating circuit for the-answerrelay R500 ofthe next succeeding storage circuit 29. At its contacts 458, the relayR450 prepares a circuit for energizing the answered signal lamps 8|9 asprovided at each of the positions of the toll operatorswitchboard. Atits contacts 458, the relay R450 opens another point in the previouslytraced circuit for energizing the unanswered signal lamp 8 8 as providedat each of -the positions of the toll operator switchboard. At itscontacts 459, the relay- R450 completes an obvious multiple circuit forenergizing the signal lamp 820 as provided at each of the positions ofthe toll relay R450 opens a point in the previously traced operatingcircuit for the marking relay R460,

As indicated above, when the cut-01f relay R440 of the storage circuit28 operates, the upper winding of the cut-off. relay R2) in the trunkcircuit 25 is energized in series with the operating winding of thesupervisory relay provided in the link l8. When thus energized, therelay R2|0 closes its contacts 2|2 to complete an obvious lockingcircuit for the switching relay R210 and, at its contacts 2, preparesthepreviously described high resistance holding circuit for itself. At itscontacts 2|3 and" 2M, the relay R2|0 completes obvious multiple holdingcircuits 'for the hold 'reits contacts 205 to interrupt the operatingand locking circuits for the three timing relays:R240, R250 and R260, aswell as the operating circuit for the storage relay R230. At itscontacts 204, the relay R200 opens the operating circuit for the holdrelay R220. At its contacts 203, the relay R200 opens a multiple branchor the circuit for energizing the upper winding of the cut-off relay-R2l0 in series with the operating winding of the supervisory relay inthe link I8. At its con-- tacts 202, the relay R200 opens another pointin the path for impressing ground potential upon the start lead 265. Atits contacts 20|, the relay R200 opens another point in the previouslydescribedring-back tone signaling circuit. Following the relayoperations just described, the call is fully extended to the No. 1position of thetoll op-' erator switchboard and the operator handlingthe call at this position may route it to its destination ina mannerwhich will be clearly apparent f romYthe foregoing description. It willbe noted that after the call is extended to the toll operatorswitchboard, all four relays R2 l0, R220, R230 and.R210 are operated inthe trunk circuit 25 while the relays R430, R440, R450, R460 and R410are operated in the storage circuit 28.

Acknowledging the stored call before it is rowted to the switchboardThe, operator attending the No. 1 position of the switchboard, uponobserving that the lamps 8|8fand 820 have been energized, is informedthat a c. call has been extended to the storagecir cuit '28, whichshould 'be acknowledged. Similar indications are provided at each of theother positions of the switchboard. In order to acknowledge thecallwithout releasing it from storage, the operator attending the No. 1position of the switchboard may actuate the answer key 800 to itsoff-normal position, thereby to completea circuit through the contacts80| for energizing the answer relay R8l0. At the contacts 805, anobviouscircuit is also completed for energizing the answer busy lamp 8|6 asprovided at each of the positions of the switchboard. i At its contacts802 and 803, the relay.R800 prepares a circuit for bridging theterminalsof the operator headsetB 5 across the talking conductors 4|a and 41b, ofthe trunk 4|. This circuit is further prepared at the contacts 8 and 8|3of the answer relay R810, when this relay operates. In operating, therelayR8|0 alsoopensits contacts 8|2 and SM to disconnect the operatorheadset from thetalking conductors823, and 824 of the operator positioncircuit I6. At the key contacts;804, an obvious circuit is completed forenergizing-; t he answer relay R130 of the common equipment-3|. Thisrelay, in operating, closes its contactsliil to prepare circuits forenergizing thelockoutrelays R450,-. R550, etc., individual :to thestorage cir-v cuits. L'At. its contacts .132, therelayR130 completes theprepared operating circuit, for .theanswer relay R490 of the storagecircuit 28, this circuit. extending from ground byway-of the contacts464, the winding of R490,,the contacts 451 and Y132, and the. resistor,13'3to battery. When thus .energized the, relay R490 opens its contacts494 to deenergize the start relay R100 of the common equipment 3|. The:latter. relay, upon restoring, closes its. contacts '102'tozrepr'eparethe operating circuit for the: reset relayR'Ll 0.

At? its contacts 10|,. the ,relay R100..- disconnects.

theistartlead 125 from ground,iwhereby thestorage-circuits arenolonger'marked ashaviiig callsstored therein in. the position distributor2| and the level marking contacts of the various position link finders.

Therelay R490, upon operating, also opens its contacts 493, thereby todisconnect-the test con-, ductor 350 of the trunk 35 from the negativeterminal of the exchange battery. Thus the path over which the rotaryposition of the trunk 35 is marked in the banks of the position linkfinders, is broken. At its contacts 495, the relay R490. completes acircuit through the contacts 485 for energizing the answer control relayR480.

In operating, the relay R480 closes its contacts 482 to complete obviousholdingcircuits forthe answer relay R490 and the control relay R410. Atits contacts 48|, the relay R480 opens the previously describedring-back tone signaling circuit, thereby to terminate the ring-backtone signal as reproduced bythe receiver of the telephone in strument atthe calling substation A. At its contacts 483, the relay R480 preparesmultiple locking circuits for'the relays R430, R440 and R450. At itscontacts484, the relay R480 opens another point in the initiallycompleted locking circuit forthe cut-ofi relay R440 The relay-R490, inoperating, also closes its contacts 491 to complete the. above-mentionedcircuit for energizing the two windings of the lookout relay R450, thiscircuit extending from ground by way of the contacts 131 to the contacts491 where it divides, one branch extending through the upper winding ofR450 to battery and the other branch extending throug'hzthe lowerwinding of R450, the contacts 453 and the resistor 438 to battery.- ,Therelay R450 doesinot operate when its twowindings are thus differentiallyenergized. It is noted, however,v that due to the presence of theresistor 438 in theicircuit for energizing the lower winding of thisrelay, the upper winding of the relay is somewhat more stronglyenergized than the lower winding thereof. At its. contacts 49| and 492,the relay R490 bridgesthe operator headset 8|5 across the talkingconductors 4|b and 4|a of the trunk 4| over a path which-includes thecondensers 134 and 135as well'as the contacts802, 803, 8| I and 8|3.When this bridging path is completed atalking circuit is set up betweenthe substation A and the operator headset 8|5, over which the operatorattending the No. 1 position of the switchboard may converse with thecalling subscriber and inform this subscriber that the handling of thecall at the toll operator switchboard must be delayed for a shortinterval. After transmitting this information to the calling subscriberthe operator may immediately releasev the talking circuit set up throughthe storage circuit 28 to the substation A by restoring the answer key800 to normal. When the key 800 is restored to normal the contactsthereof are opened to deenergize the answer relay R8|0 and the contacts802 and 803 thereof are opened to interrupt the talking circuit asestablished between the. operator headset 8|5 .and the callingsubstation. At the contacts 805, the circuit for energizing the answerbusy lamp, 8|6 as provided at each of the several positions of theswitchboard, is opened. At the contacts 804,-the operating circuitforthe answer relay R is interrupted.

e asin he e ay R130 opens its contacts 132 to deenergize the answerrelay R490 of the storage circuit 28. At its contacts 13I, the relayR130 interrupts the above-traced circuit for energizing the R45UI11I1opposition. When this circuit'is broken,

two windings 'of the lockoutrelay the inductive kick produced in theupper winding of the relay R450. reverses the direction of current fiowthrough the lower winding thereof and momentarily. builds up a magneticfield of sufiicient strength tocause therelay to close itspreliminarymake, contacts 452 When this occurs, the'two windings of the relay R450are energized in'series aiding, relationship over a circuit whichextends to ground through the contacts. 466. When the latter circuit iscompleted the relay R450 completes its operation to perform the func-'tiolis dcs cribed above.

' The relay R490, upon restoring in response to" the releaseof theanswer relay R130, opens its contacts 495to deenergize'the answercontrol relay R480. At its contacts 494, the relay R490 recompletes theoperating circuit for the start relay R100 of the common equipment 3|.At its contacts 493, the relay R490 recompletes the previously tracedpath for impressing negative battery potential upon the test conductor350 for the purpose of marking the rotary position of the trunk 35 inthe banks of the position link finders. At its contacts 49l and 492, therelay R490 opens two additional points in the previously traced talkingcircuit set up between the operator headset 8|5 and thecalling'subs'tation A. At its contacts 491, the relay-R490 opens anotherpoint in the circuit for energizing the two' windings of the lockoutrelay R450 in opposition. The answer control relay R480, upon restoring,closes its contacts 481' to recomplete the ring-back tone signalingcircuit, opens its contacts 482 further to interrupt the multiplecircuits for energizing the relays R410 and R490,'andopens its contacts483 to interrupt the prepared locking circuits for the three relaysR430, R440 and R450. At its contacts 484, the relay R480 re-prepares theinitially traced locking circuit for the cut-off relay R440.

The start relay R100 of the common equipment 3|, upon reoperating,closes its contacts 10l to again mark the vertical position of thestorage trunks 35, 36, 31, etc. in the banks of the position linkfinders and to again mark the various storage circuits as being occupiedwith calls in the position distributor 2|. At its contacts 102, therelay R100 opens the operating circuit for the reset relay R110.

Routing the stored'call to the switchboard after it has beenacknowledged After the call has been acknowledged by the operatorattending the No. 1 position of the switchboard in the manner justexplained, and when one of the positions of this switchboard becomesidle for call assignment by the position distributor 2|, the call asstored in the storage circuit may be released from storage and extendedthrough one of the position links to the operator position circuit ofthe assigned position in the exact manner explained above Withreferenceto the release of a call from storage before itis acknowledged.In the present case, however, the lockout relay R450 occupies itsoperated position before the call is released from storage. The factthat this relay is operated does not, however, alter in any way themanner in which a connectionis extended over the trunk 35 to the tolloperator switchboard when a position of this switchboard is selected tohandle the call by the distributor2l.

' The call is abandoned If the calling party abandons the call while itis-being held in the storage circuit 28, the trunk circuit oceupied;with the call'is released but gag-1 0% the storage cifrcuit ztis heldout of service until reallotted for use'un der the control of the commonequipment :31. More specifically, when the calling partly disconnects;the toll s'elector l4, the first selector I I, and the line switch 9 arere-' leased in ,the exact manner explained" above. Incidenttotherel'eafse of the-toll selector l4, the private wiper I40 ther-eofisdisconnected from ground to deenergize the answer relay R200.'Uponfrestoring, therelay'R200 opens its contacts 20lfurther'tointerrupt the initially completed ring-back tone signalingcircuit. At itscontacts 202, the; relay R200 opens another'point' in thepath for impressingjground potential "upon the start'le ad 265'. At itscontacts 203, the relay R200 opensone'o f the multiple operatingcircuits for the cut-off relay R2I0. At its contacts 205, -th'e relay 1R200,opens another pointin the common portion of the operating andlocking circuits for the three timing relaysR240/R250 and} R260. At itscontacts 204, the relay R200 deenergizes the;hold relay R220'andthestorage relay R230. In releasing, the relay R220 closes its contacts 22!to again bridge the terminating" impedance comprising the resistor 20 6and the condenser 201 across the talking conductors 32a and 32b of thetrunk .32. .At its contacts 222, the relay R220 opens the multiplebranch of the operating circuit for the cut-off relay R2l0. At itscontacts 223, the relay R220 opens a point in its own looking circuit.At its contacts 224, the relay R220 prepares the previously describedpath for impressing ground potentialupon the test conductor 32c.

The storage relay R230; upon restoring, opens its contacts 233todeenergize the series-connectedrelays R210 andR460, causing both ofthese relays to'restore. At its'contacts 232, the relay R230 repreparesthe path for impressing ground potential upon the start lead 265. At itscontacts'231, the relay R230 reprepares the path for impressing negativebattery potential upon the test conductor 32d. At its contacts 234, therelay R230 opens another point in the path for impressing groundpotentialon the test conductor 38s. At its contacts 235, the relay R230opens another point in its own locking circuit. At its contacts 236, therelay R230 reprepares the operating and locking circuits for the threetiming relays R240, R250-and R260. At its contacts 231, the relay R230opens another point in the path for impressing ground potential upon thestart lead 2 in the trunk circuit 25. l

The relay R210, in releasing, closes its contacts 211 to reprepare thepath for impressing ground potential upon the start lead 214 in thetrunk circuit 25, and closes its contacts 216 to reprepare the path forconnecting the test conductor 38sto ground. At its contacts 215, therelay R210 opens a point in its own locking circuit. At its contacts214, the relayR210 opens a point in one of the previously tracedoperating circuitsfor, the cut-off relay R2l0. At its contacts 2H and213, the'relay R210 disconnects the talking con-. ductors 38a and 38b ofthe trunk 38 from the: corresponding-talking conductors of the trunk 32.At its contacts 212, the relay R210 reprepares the ring-back tonesignaling circuit asprovidedin the trunk circuit 25. V

LWhenthe marking relay R460 is. deenergized'in response to therelease ofthe storage' relay R230, itv opens'its contacts 462 further tointerruptiits. own' locking circuit. At its contacts 46 l, the relay:R460 disconnects the test conductor 350. from: a the negative: terminalof: the exchange battery-.1

At its'contacts 463, the relay R460 completes an obvious circuit forenergizing the cut-01f relay R440, which circuit extends to groundthrough the contacts 413. At its contacts 464, the relay R460deenergizes the control relay R410. At its contacts 465, the relay R460completes another locking circuit for the relay R450. At its contacts461, the relay R460 completes an additional set of locking circuits forthe relays R430 and R450, which circuits commonly extend to ground overa path including th contacts 484 and 123. After completing the lattercircuits; the relay R460 opens its contacts 466 to interrupt the locallocking circuits for the relays R430 and R450. At its contacts 468, therelay R460 opens a point in the common portion of the circuits forenergizing the answered and unanswered signal lamps as provided at thetool operator switchboard.

The cut-off relay R440, upon operating, locks to ground through itspreliminary make contacts 441 and the contacts 461, 484 and 123. It alsolocks to ground over a path including the contacts 441, 441, 414 and465. At its contacts 441', it-completes an obvious multiple holdingcircuit for the rela R430. At its contacts 448, the relay R440 closes apoint in the chain path for impressing ground potential upon the A. T.B. lead 209.: At its contacts 446, the relay R440 opens the operatingcircuit for the start relay R100. The remaining circuit switchingoperations performed by the relay R440 are without effect.

The control relay R410, upon restoring, opens its contacts 413 and 414to interrupt two sets of the circuits over which the three relays R430,R440 and R450 are energized, leaving these three relays locked up incircuits which commonly extend to ground through the contacts 123 of thereset slave relay R120. The three enumerated relays remain in theiroperated positions to prevent the storage circuit 28 from storing otherC. L. R. calls. until such time as the reset relays R1I0 and R120 areoperated to reallot the several storage circuits for further use.

'In the event the storage circuit 28 is the only storage circuitoccupied with a call, the start relay R100 is deenergized and restoresin response to the operation of the relay R440. In releasing, the relayR100 closes its contacts 102 to reprepare the operating circuit for thereset relay R1I0. At its contacts I, the rela R100 disconnects the startlead 125 from ground. In the event the above-described call as stored inthe storage circuit 28 is not extended to the toll operator switchboardor acknowledged by an operator attending one of the positions of thisswitchboard prior to the abandonment of the call at-the substation A,the cut-off relay R440 and the lockout relay R450 are not operated inthe storage circuit 28 at the time thecalling subscriber disconnects.Under these circumstances, the relay R440 is energized through thecontacts 463 and 413 and the relay R450 is energized in a circuitincluding the contacts 465 and 414, in response to the release of'themarking relay R460. In operating, the relay R450 locks to ground throughits preliminary make contacts 452 and thecontacts 461, 484 and 123. Therelay R440 locks to ground over the same path. Thus, reardless ofwhether or not the call as stored in the storage circuit 28 is abandonedbefore or after it is acknowledged at the toll operator switchboard,-'the three relays R430, R440 and R450 are locked in their respectiveoperated posi' tionsafter the trunk circuit 25 is released.

Releasing the equipment after'the call is released 5 from storage If thecall as stored in the storage circuit 28 is released from storage andextended to the No. 1 position of the toll operator switchboard throughthe link I8, for example, and is then released at the callingsubstation, the trunk circuit 25 occii pied with the call is releasedand the storage circuit 28 assumes its lockout setting. Morespecifically, when the calling party disconnects to cause the release oftheswitch train comprising the selectors I4 and I I and the line switch9, the test lead 320 is disconnected from ground in the selector I4 tocause. the deenergization .and release of the two relays R220 and R230.The relay R220, in restoring, opens its contacts 222 to give theoperator handling the call disconnect supervision and, at its contacts224, applies guarding ground potential to the test conductor 320 toguard the trunk circuit 25 against seizure. Following the release of thetoll selector I4 the cut-ofi relay R2I0 and the switching relay R210remain operated in the trunk circuit 25'until such time as theconnection is released .by the operator attending the No; 1 position ofthe switchboard. When this operator releases the link I 8 occupied withthe call in the manner [previously described, the testv conductor 35cisdisconnected from ground in this link to cause the release of thecut-off relay-R2I0'in the trunk circuit 25. Upon restoring, the relayR2I0 opens its contacts 2 I2 to deenergize the switchingrelay R210 andthe marking relay'R460. At its con-.' tacts 2I3 and 2I4, the relay R2I0disconnects the test conductor 320 from ground and cone nectsthisconductor to the negative terminal of the exchange battery, thereby tomark the trunk circuit 25 as idle in the banks of the toll selectorshaving access thereto. Followingr'the release of the two relays R2I0 andR210, the trunk circuit 25 is fully restored to normal and-is renlderedavailable for handling other C. L. R. ca s.

The marking relay R460, upon restoring, per forms the functionsdescribed above in connece tion with the abandonment of a call before itis acknowledged at the toll operator switchboard. Following the releaseof this relay, the three relays R430,R440 and R450 are locked operatedin the storage circuit 28 under the control of the reset slave relay Rof the common equipment 3I. Thus, the storage circuit 28 is preventedfrom receiving another callfuntil such time as the two reset relays R1I0and R120 have been operated to reallot the idle'storage circuits forfurther use. I Storing and acknowledging other C. L. R. calls From thepreceding explanation it will be understood that immediately after thefirst storage circuit 28 operates to store the call originating at thesubstation A, the next-succeeding storage circuit 29 is conditioned tostore another 0. L. R. call extended to one of the C. L, R. trunkcircuits 26, 21, etc. Thus, when the test relay R430 operates incidentto the operation of the trunk finder switch 400 to seize the callingtrunk circuit 25, it opens its contacts 436 to deenergize the startrelay R420, and closes its contacts 435 to prepare the operating circuitforthe start re lay R520 of the next succeeding storage circuit 29; Thiscircuit is further prepared at the'contacts 423 incident to the'rcleaseof the start relay R420 'inthe first storage circuit. 'It wurbeunderstood,- therefore,-ithat if a second callis extended to thetrunkcircuit'l li, for example, at atime when all of the positions ofthe toll operator switchboard are busy, it will be stored in the storagecircuit 20. Thus, when the timing relays of'the second trunk circuit 26operate to connect the start lead 2| 4 to ground, the start relayR520 ofthe second'storage circuit 20' is energized in a circuitwhichincludes'the contac'ts435, 423, 536 and 556. This re lay,.inoperating, causes the trunk finder switch-500 included in the storagecircuit 29 to operate and seize thestorage trunk 39 extending to thetrunk circuit 26 occupied with the call. The, manner infwhich the'secondstorage circuit 29'operates to'handle the call is in all respectsidenticalwith that of the storage circuit 28 as described above. Inithisregardit' will be noted that after, the test re1ayj'R530 is operated andthe start relay R520 ha'sijrestqred, the start'circuit including theconductor 214 is extended to the start relaycf the third storagecircuit, whereby the-C. L. R. call next initiated at a time when all ofthe positions of the toll operator switchboard are busy is stored in.thefthird' storage circuit. More generally con sidered, the calls arestored in successive ones of the available storage circuits in the orderof their initiation. i

From the above explanation it will be understODd that the storagecircuits are used in succe'ssion to receive the calls requiring storage,regardless of whether. such calls overlap. Thus, even iftheabove-described call as extended to the first storage circuit 28 isabandoned, either before or after acknowledgment, or is routed to thetoll operator switchboard, forwarded tofits destination and thenreleased, the test relay R430 is'held in its operated position under thecontrol of the .reset relays R110 and R120 as provided in the" commonequipment 3|. Similarly, after a' call is once stored in the secondstorage circuit 29; the test relay R530 remains in its operated positionuntil such time as the two reset relays R1l0 and R120 are operated. Thisarrangement insures that the'storage circuits will be used in rotationand, further, that overlappin C. L. R. calls -wil1 be stored therein ina predetermined order.

pItis noted further that the storage trunks 35, 36, 31, etc., individualto the storage circuits are terminated in the bank contacts of theposition link finders in such order that the stored callswill-bereleased from storage in the same order that they are stored.Thus, the conductors of the first storage trunk .35 are terminated inthe first set of contacts of the storage level in each of the positionlink finder banks, whereby the wipers of any one of the finders insearching for a storage trunk will encounter the contacts terminatingthe conductors of the trunk 35 before reaching the contacts terminatingthe conductors ofthelstorage trunks extending to the intermediate andlast storage circuits. The arrangement of the equipment is also suchthatcalls stored in the various storage circuits can only 'beacknowledged by the operators attending the toll operator switchboard ina predetermined order. In this regard it will be recalledthat when theabove described calloriginating'at the substation A is stored in thestorage-circuit 28, the lookout relay R450 is operated incident to theacknowledgment of the call at the toll' operator switchboard. With thisrelay operated, the operating circuit for' the answer relay--R490 ii-heldopen'at thecontacts 451' and contacts 451;

the operating circuit for the answerrelay-RSSO of the second storagecircuit 29 is prepared atithe Accordingly, if. the answer relay R130 inthe common equipment 3| is reoperated, the answer relayR590 is energizedin a circuit which includes the answer lead 136, the contacts 451, '551and .554. When the lockout relay R550 of the second storage circuit issubsequently op.- erated in response to the release of the answer, relayR130, it opens its contacts 551' to prevent subsequent energization ofthe answer relay R590, and closes its contacts 551 to eXtendthe answer.lead to the winding of the answerrelay in the next succeeding storagecircuit. Thus, it 'willlbe' understood that the stored .calls can onlybe acknowledged by the operators attending the toll operator switchboardin a predeterminedorder.

Release of the Storage circuits After each of the call storagecircuits'has received a call for storage and all such calls -have eitherbeen abandoned or extended to thetoll operator switchboard in the mannerpreviously explained, all of the idle storage circuits are automaticallyreleased whenthe next C. L. RS call requiring storage is routed to oneof the various trunk circuits. Thus, it will be noted that when the testrelay R630 of the last storage circuit operates to release itsassociated start relay R620, the start circuit is'extended through thecontacts 535 and 623 to the contacts 102 :of the start relay R in thecommon equipment 3!, thereby to prepare the operating circuit for theslow-to-operate reset relay R1I0. It will also be noted that theoperating circuit for the start relay R100 includes parallel branchesindividual to the various storage circuits, which branches respectivelyinclude the contacts 446, 546, T646, etc, of the cut-offrelaysindividual to the star age circuits. "Accordingly, so long as anystored call has not been abandonedand has not been extended to the tolloperator switchboard through one of the positiorr'links' associated withthis switchboard, the start relay R100 is held'operated over the branchof its'operating circuit which? is completed inv the storage circuitoccupied" with the call that has not been released from storage; When,however, the last stored 'call is released from storage, the"cut-offrelay', such; for exam; ple, as the relay 'R640 of the storagecircuit-oc cupied with the 'call,'is' operated to deener'gi'ze' thestart relay R100: This relay, in releasing; closes its contacts 102 toprepareor completethe operating circuit for thereset relay R1I0; :Thus;if one of'the trunkcircuits, such, for example; as the trunk circuit 25is occupied with a call awaitingstorage; the timing relays R240,*R250and R260 operate tomeasure a predetermined time interval, after whichthe storage relay R230 is energized, all in the manner previouslyexplained. In' the present case, the previously mentioned chain path forconnecting theA. T; B;- lead 209-to ground'is" utilized toprovidecircuits for energizing the four enumerated t relays. More specifically,this path extends from the lead 209-by way"of thechain-connectedcontacts 648, 548, 448, etc., controlled by therespective cut-off relays-of the'various storage'circuits; to theconductor 485. From this point branch paths extend to ground in eachof'the storage-circuits not'occupied with a call. Thus; if the firststorage circuit 28 occupiesits lockout-setting; the conductor 485isconnected to'ground through the contacts 454' and 415. --Similarly, ifthesecond storage circuit- -29 occupies; its -=lockoutsetting-;

